module.exports = function (hljs) {
  // Data step and PROC SQL statements
  var SAS_KEYWORDS = '' +
        'do if then else end until while ' +
        '' +
        'abort array attrib by call cards cards4 catname continue ' +
        'datalines datalines4 delete delim delimiter display dm drop ' +
        'endsas error file filename footnote format goto in infile ' +
        'informat input keep label leave length libname link list ' +
        'lostcard merge missing modify options output out page put ' +
        'redirect remove rename replace retain return select set skip ' +
        'startsas stop title update waitsas where window x systask ' +
        '' +
        'add and alter as cascade check create delete describe ' +
        'distinct drop foreign from group having index insert into in ' +
        'key like message modify msgtype not null on or order primary ' +
        'references reset restrict select set table unique update ' +
        'validate view where'

  // Built-in SAS functions
  var SAS_FUN = '' +
        'abs|addr|airy|arcos|arsin|atan|attrc|attrn|band|' +
        'betainv|blshift|bnot|bor|brshift|bxor|byte|cdf|ceil|' +
        'cexist|cinv|close|cnonct|collate|compbl|compound|' +
        'compress|cos|cosh|css|curobs|cv|daccdb|daccdbsl|' +
        'daccsl|daccsyd|dacctab|dairy|date|datejul|datepart|' +
        'datetime|day|dclose|depdb|depdbsl|depdbsl|depsl|' +
        'depsl|depsyd|depsyd|deptab|deptab|dequote|dhms|dif|' +
        'digamma|dim|dinfo|dnum|dopen|doptname|doptnum|dread|' +
        'dropnote|dsname|erf|erfc|exist|exp|fappend|fclose|' +
        'fcol|fdelete|fetch|fetchobs|fexist|fget|fileexist|' +
        'filename|fileref|finfo|finv|fipname|fipnamel|' +
        'fipstate|floor|fnonct|fnote|fopen|foptname|foptnum|' +
        'fpoint|fpos|fput|fread|frewind|frlen|fsep|fuzz|' +
        'fwrite|gaminv|gamma|getoption|getvarc|getvarn|hbound|' +
        'hms|hosthelp|hour|ibessel|index|indexc|indexw|input|' +
        'inputc|inputn|int|intck|intnx|intrr|irr|jbessel|' +
        'juldate|kurtosis|lag|lbound|left|length|lgamma|' +
        'libname|libref|log|log10|log2|logpdf|logpmf|logsdf|' +
        'lowcase|max|mdy|mean|min|minute|mod|month|mopen|' +
        'mort|n|netpv|nmiss|normal|note|npv|open|ordinal|' +
        'pathname|pdf|peek|peekc|pmf|point|poisson|poke|' +
        'probbeta|probbnml|probchi|probf|probgam|probhypr|' +
        'probit|probnegb|probnorm|probt|put|putc|putn|qtr|' +
        'quote|ranbin|rancau|ranexp|rangam|range|rank|rannor|' +
        'ranpoi|rantbl|rantri|ranuni|repeat|resolve|reverse|' +
        'rewind|right|round|saving|scan|sdf|second|sign|' +
        'sin|sinh|skewness|soundex|spedis|sqrt|std|stderr|' +
        'stfips|stname|stnamel|substr|sum|symget|sysget|' +
        'sysmsg|sysprod|sysrc|system|tan|tanh|time|timepart|' +
        'tinv|tnonct|today|translate|tranwrd|trigamma|' +
        'trim|trimn|trunc|uniform|upcase|uss|var|varfmt|' +
        'varinfmt|varlabel|varlen|varname|varnum|varray|' +
        'varrayx|vartype|verify|vformat|vformatd|vformatdx|' +
        'vformatn|vformatnx|vformatw|vformatwx|vformatx|' +
        'vinarray|vinarrayx|vinformat|vinformatd|vinformatdx|' +
        'vinformatn|vinformatnx|vinformatw|vinformatwx|' +
        'vinformatx|vlabel|vlabelx|vlength|vlengthx|vname|' +
        'vnamex|vtype|vtypex|weekday|year|yyq|zipfips|zipname|' +
        'zipnamel|zipstate'

  // Built-in macro functions
  var SAS_MACRO_FUN = 'bquote|nrbquote|cmpres|qcmpres|compstor|' +
        'datatyp|display|do|else|end|eval|global|goto|' +
        'if|index|input|keydef|label|left|length|let|' +
        'local|lowcase|macro|mend|nrbquote|nrquote|' +
        'nrstr|put|qcmpres|qleft|qlowcase|qscan|' +
        'qsubstr|qsysfunc|qtrim|quote|qupcase|scan|str|' +
        'substr|superq|syscall|sysevalf|sysexec|sysfunc|' +
        'sysget|syslput|sysprod|sysrc|sysrput|then|to|' +
        'trim|unquote|until|upcase|verify|while|window'

  return {
    aliases: ['sas', 'SAS'],
    case_insensitive: true, // SAS is case-insensitive
    keywords: {
      literal:
                'null missing _all_ _automatic_ _character_ _infile_ ' +
                '_n_ _name_ _null_ _numeric_ _user_ _webout_',
      meta:
                SAS_KEYWORDS
    },
    contains: [
      {
        // Distinct highlight for proc <proc>, data, run, quit
        className: 'keyword',
        begin: /^\s*(proc [\w\d_]+|data|run|quit)[\s\;]/
      },
      {
        // Macro variables
        className: 'variable',
        begin: /\&[a-zA-Z_\&][a-zA-Z0-9_]*\.?/
      },
      {
        // Special emphasis for datalines|cards
        className: 'emphasis',
        begin: /^\s*datalines|cards.*;/,
        end: /^\s*;\s*$/
      },
      { // Built-in macro variables take precedence
        className: 'built_in',
        begin: '%(' + SAS_MACRO_FUN + ')'
      },
      {
        // User-defined macro functions highlighted after
        className: 'name',
        begin: /%[a-zA-Z_][a-zA-Z_0-9]*/
      },
      {
        className: 'meta',
        begin: '[^%](' + SAS_FUN + ')[\(]'
      },
      {
        className: 'string',
        variants: [
          hljs.APOS_STRING_MODE,
          hljs.QUOTE_STRING_MODE
        ]
      },
      hljs.COMMENT('\\*', ';'),
      hljs.C_BLOCK_COMMENT_MODE
    ]
  }
}
